Field of the Invention
The invention relates to a system for monitoring units excited by oscillations, having the features stated in the preamble of claim 1.
It is known from U.S. Pat. No. 4,612,620 to monitor units excited by oscillations by means of a so-called route. For the purposes of the present description, units excited by oscillations are understood to mean one or more machines, production installations, auxiliary devices, components or other installations of any kind which are to be regarded in a certain association with one another, for example that they all belong to one and the same plant. The route comprises defined measuring points being allocated a measuring task in a specific sequence within a specific period of time at the units. For this purpose, a portable measuring apparatus is provided, having operator-control elements, memories, microprocessors and a display. Measuring tasks relevant for each ofthe possible measuring points can be stored with associated, suitable measurement settings in this measuring apparatus via a higher-level computer (central processing unit). Consequently, a specific measurement, for example frequency analyses of oscillations etc., can be carried out at each measuring point by means of this portable measuring apparatus. The measurement results thus obtained are stored in the portable measuring apparatus. Once the route has been patrolled, the portable measuring apparatus can be connected again to the higher-level computer, whereupon an evaluation of all the stored measurement results of all the measuring points allocated a measuring task takes place.
Consequently, it is a principal characteristic of the route that the measuring tasks are stored in the sequence of later processing in the central processing unit and that this sequence is transmitted to the measuring apparatus, so that the measuring tasks are automatically displayed in the prescribed sequence in the measuring apparatus.
It is known to use as measuring tasks the measuring of individual measured variables for an assessment of the state of the unit having the measurng points. These individual measured variables are not specific to the respective measuring points, but are regularly recorded according to the route laid down and, after transferring the measurement results into the central processing unit, are supplied with regard to a trend in the development of the measurement results and/or to a threshold-value comparison. Since, as is known, an actual identification of the cause of an error can only take place by means of a signal measurement, preferably with specialists being able to assign specific lines in recorded frequency spectra to specific causes of error in the evaluation. To carry out these signal measurements, a second patrol of the route is required, in order that the signal measurements can be carried out at those measuring points determined with the first patrol of the route at which the evaluation of the individual measured variables which have been measured indicates that a threshold value had been exceeded. To be able to carry out this second patrol of the route, a listing of specific measurement settings of the signal measurements by a specialist is required, either at the central processing unit or in situ, at the respective measuring point on the measuring apparatus.
A further known route comprises carrying out complete signal measurements at each selected measuring point of the route, without an assessment of the state of this measuring point having taken place beforehand using an individual measured variable. Since the signal measurements for monitoring units excited by oscillations, for example a frequency analysis, are relatively complicated, the measuring apparatus must have a correspondingly great capacity. In particular, there must be sufficient storage space for storing the measuring tasks, the measuring programs and the measurement results; what is more, a relatively complex software package must be kept for the proper processing of these points.